John James Jacoby

Matt Mullenweg

Samuel Wood (Otto)

It’s hard to keep up with a private blog because there’s no good way to subscribe to it. Subscription plugins aren’t great because generally you have a finite number of people you want to get to it and asking each one to do a double-opt-in is annoying, and you still wouldn’t have anything for comments.
This hooks into the new comment and new post actions to send an email to the addresses you enter, so it’s easy to follow the entire conversation even if it’s comments on someone else’s blog posts.

Notifly

Send notification emails of all new posts and new comments to everyone on a list. Great for private blogs.

dxladner

This multisite compatible plugin allows users to subscribe to your blog using a customized form. Users will have the ability to subscribe to your blog, verify their subscription and unsubscribe. 
Your subscribers can be viewed from a dashboard in the admin section. You can see their subscription status, the data they unsubscribed and delete any subscribers. When a user 
subscribes to your blog using the form a verification email is sent to their email address. In the email there is a Verify button that the subscriber will click that then 
changes the subscribers status from Unverified to Subscribed. When you Publish a new post, all of your subscribers will receive an email announcing a new Post was Published with 
a link in the email back to that post for their reading. Also inside all Published Posts emails, there is an Unsubscribed link. So if a subscriber wishes to Unsubscribe from 
your blog, they can click the Unsubscribe link and their status will change from Subscribed to Unsubscribed and will no longer receive emails when you Publish a new Post. 
There are some limited custom settings in the Lite version for the form and the email content.
Using the following shortcode [ruasubscriber], you can place the Subscription Form on a page or post. If you would like to place the shortcode in a widget 
you will need to use the Shortcode Widget Plugin. The Shortcode Widget plugin is a Free plugin from the WordPress Directory which allows you to place 
shortcodes in a widget. Out of the box, WordPress Widgets cannot handle shortcodes.
Get the <a href="https://wordpress.org/plugins/shortcode-widget/" rel="ugc">Shortcode Widget Plugin here</a>.

RUA Blog Subscriber Lite

Build your email list! Manage Subscribers from a Dashboard. Custom settings. Notify users of new posts. All without having users create accounts.

Notifly vs RUA Blog Subscriber Lite